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Online – only Data Supplement Cyclic Nucleotides Differentially Regulate Cx 43 Gap Junction Function in the Ovine Uterine Endothelium during Pregnancy
| Content Provider | Semantic Scholar |
|---|---|
| Author | Ampey, Bryan C. Ampey, Amanda C. López, Gladys E. Bird, Ian M. Magness, Ronald R. |
| Copyright Year | 2017 |
| Abstract | Cell to cell communication is vital for the development of cardiovascular adaptations during gestation and are reliant on GJ (gap junction) intercellular communication (GJIC). GJs are specialized membrane hemichannels composed of Cx (connexin) proteins that direct cell–cell diffusion of ions, small molecules, and second messengers (eg, IP3, Ca, cAMP, cGMP, ATP) that are important for synchronizing endothelial cell vasodilatory responses. Pregnancy is a physiological state of vasodilation that requires heightened cell coupling to maintain substantial increases in blood flow necessary for fetal growth and development. Endothelialderived vasodilators, such as prostacyclin (PGI 2 ) and nitric oxide (NO), are enhanced in the uterine circulation during pregnancy and serve as a pregnancy-adapted vasodilatory phenotype that sets the stage for the pronounced gestational elevations in uterine blood flow. We have shown that Cx43 is the major GJ protein present in uterine artery endothelial cells (UAECs) and controls pregnancy-specific Ca–mediated activation of endothelial NO synthase and NO production in vitro and ex vivo. In hypertensive states of pregnancy, reduced vasodilation is related to endothelial cell dysfunction characterized by reduced bioavailability of endothelium-derived vasodilators, in particular NO. Aberrant Cx43 expression, function, and lack of sufficient NO production are associated with hypertension. Because endothelial cell dysfunction is linked to impaired endothelium-dependent vasodilation mechanisms, hypertensive diseases of pregnancy, such as preeclampsia, may very well occur at least in part because of Abstract—Cell–cell communication is dependent on GJ (gap junction) proteins such as Cx43 (connexin 43). We previously demonstrated the importance of Cx43 function in establishing the enhanced pregnancy vasodilatory phenotype during pregnancy in uterine artery endothelial cells from pregnant (P-UAEC) ewes. Cx43 is regulated by elevating cAMP and PKA (protein kinase A)–dependent Cx43 S365 phosphorylation–associated trafficking and GJ open gating, which is opposed by PKC (protein kinase C)–dependent S368 phosphorylation-mediated GJ turnover and closed gating. However, the role of cyclic nucleotide-mediated signaling mechanisms that control Cx43 and GJ function in P-UAECs is unknown. We hypothesize that cAMP will mediate increases in S365 phosphorylation, thereby, enhancing GJ trafficking and open gating, while cGMP will stimulate S368, but not S365, phosphorylation to enhance GJ turnover and closed gating in P-UAECs. Treatment with 8-Bromo (8-Br)-cAMP signal significantly (P<0.05) increased nonphosphorylated S365 signal and total Cx43 phosphorylation, but not S368 phosphorylation, while 8-Br-cGMP significantly (P<0.05) increased Cx43 C-terminus-S365 signal, S368, and total Cx43 phosphorylation. Inhibition of PKA, but not PKG (protein kinase G), abrogated the 8-Br-cAMP–stimulated increase in nonphosphorylated S365 and total Cx43 phosphorylation and inhibited S368 below basal levels, whereas inhibition of PKG blocked (P<0.05) the 8-bromo-cGMP-stimulated rises in nonphosphorylated S365, total Cx43, and S368 phosphorylation levels in P-UAECs. Functional studies showed that 8-Br-cAMP increased dye transfer and sustained calcium bursts, while 8-Br-cGMP decreased both. Thus, in P-UAECs, only 8-Br-cAMP and not 8-Br-cGMP effectively enhances nonphosphorylated S365 and total Cx43 expression that correspondingly reduces S368 phosphorylation, allowing increased GJ communication. This provides new insights into the regulatory mechanisms behind Cx43 function and GJ communication. (Hypertension. 2017;70:401-411. DOI: 10.1161/HYPERTENSIONAHA.117.09113.) • Online Data Supplement |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://hyper.ahajournals.org/content/hypertensionaha/70/2/401.full.pdf?download=true |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
